1. Field of the Invention
The present invention relates to Points of Presence (PoPs). More particularly, the present invention relates to the sharing of Network Access Server (NAS) information between PoPs in order to more effectively handle user roaming.
2. The Background
Turning to FIG. 1, one approach for providing network access to a communications system 8 over an access point (such as access point 10a, access point 10b, or access point 10c) using a communications network 12 is shown. An access point is associated with a set of service components and at least one client, enabling a subscriber 14 using a host machine 16, such as a personal computer having a modem, to obtain access to system 8. As known to those of ordinary skill in the art, when referred to in the context of the Internet or other large computer networks, each client coupled to an access point provides connectivity to hosts within an area commonly referred to as a PoP or “Point of Presence.” A PoP is a geographical area that is serviced by an access point, which is typically managed by an ISP (“Internet Services Provider”). For dial-up access methods using a public switched telephone network (PSTN), the geographical area may be defined by an area code.
For example, if network 12 is implemented using the Internet, access point 10a may be configured to support subscribers within a geographical area defined by a first area code, such as that covering San Jose, Calif., while access point 10b may be configured to support subscribers within another geographical area defined by a second area code, such as that covering San Francisco, Calif. and/or its surrounding cities and towns. Similarly, access point 10c may be configured to support subscribers within a geographical area defined by a third area code, such as that covering New York City, N.Y.
For dial-up access to network 12, each access point includes at least one network access server (commonly referred to as a NAS), such as network access server 18. Network access server (NAS) 18 functions as an interface between host machine 16 (via the modem) and the necessary services which must be provided when subscriber 14 seeks to obtain network access using a dial access method. Each PoP may contain one or more NASes. Responding to a dial-up access request typically includes the process steps (sometimes referred to as “states”) of authentication, authorization, and accounting. These states may be provided by an Authentication, Authorization, and Accounting (AAA) server, such as AAA server 20. AAA server 20 uses the RADIUS protocol to communicate with devices, such as network access server 18, which request authentication, authorization, and accounting services.
To provide authentication, authorization, and accounting services properly, an AAA server requires access to a database 22 having a set of user records. The user records are then accessed during authentication, authorization, and/or accounting. For a communications system that has more than one access point, such as communications system 8, database 22 may be maintained as a central database that contains all of the user records required by all of the access points in communications system 8. This provides the advantages of maintaining only one database for more than one access point, reducing the complexity of the system, while permitting a subscriber to obtain network access at an access point other than his originating access point (commonly referred to as “roaming”).
For example, if access point 10a is the home access point for subscriber 14, subscriber 14 may still dial-up a different access point, even if the access point is at a different geographical area, such as access point 10c. This is possible because access point 10c has access to the user record corresponding to subscriber 14 by virtue of database 22.
However, centrally locating a database is expensive with respect to network bandwidth consumption because each database transaction generated for every access request that requires AAA services from an access point in communications system 8 must be sent to database 22 (sometimes referred to as “back-hauling”). Moreover, this problem of bandwidth consumption increases and becomes more acute during peak use hours.
Back-hauling also requires an entry for each NAS in the AAA server database, because the AAA server database must authenticate the NAS from which the user is accessing the network.
Another solution involves implementing a local database at each access point. This case is illustrated in FIG. 2. Each database 50a, 50b, 50c contains a complete set of user records. This allows a user to easily roam, as the user's record is accessible from any of the NASes. However, this solution offers the challenges of having to maintain synchronicity with other local databases. Each time a user's record is changed, added, or removed, all the local databases must be updated.
It is also becoming more common for ISPs to enter into partnership or “roaming” agreements with other ISPs to provide access to each other's subscribers. This type of roaming is fairly common with cellular phones, where a user may have a plan with a local cellular phone service, but when traveling must utilize another company's service in order to use the same cell phone. The local cellular phone service normally has agreements with cellular phone services throughout the country to provide access. This type of roaming may also be utilized for ISPs. Centralizing a database of user records may be difficult or impossible because of the security concerns about giving more than one ISP access to a particular user's record. The same security concern exists for having local databases containing the entire database of user records.
Accordingly, a need exists for a solution that allows for roaming capabilities, but which limits the bandwidth consumption normally encountered with current solutions.